This invention relates to a disk player for reproducing data recorded on a recording disk.
Recording disks include CAV (constant angular velocity) disks and CLV (constant linear velocity) disks. In the case of a CAV disk, a predetermined amount of data such as a frame of video data has been recorded in each circumferential track coaxially arranged on the disk, and the parts of the tracks which are located between the frames and in which data corresponding to vertical synchronizing signals have been recorded are arranged on a straight line extended radially. Therefore, with a CAV disk, the synchronizing signals of video signals reproduced are regular in period even immediately after a jumping operation. That is, the CAV disk is suitable for a special picture reproduction such as a still picture reproduction.
On the other hand, in the case of a CLV disk, different amounts of data are recorded in different circumferential tracks; for instance, one frame of video data is recorded in the innermost circumferential track while three frames of video data is recorded in the outermost circumferential track. Therefore, with a CLV disk, the synchronizing signals of a video signal reproduced immediately after a jumping operation is irregular in period. In order to overcome this difficulty, a data reproducing device has been proposed in the art in which a video memory capable of storing one frame or field of video signals is provided, video signals are stored at predetermined positions in the video memory and are read out with an external stable clock signal.
It is desirable for the data reproducing device to be able to insert patterns such as characters and numerals including data such as frame numbers and chapter numbers not only in a picture reproduced by the video signal which is read from the disk and outputted as it is (without using the video signal which is read out of the video memory). In order to meet this requirement, it is necessary to provide a circuit for inserting a video signal corresponding to a pattern containing predetermined data in the video signal read out of the disk, and another circuit for inserting such a video signal in the video signal read out of the video memory. This will undoubtedly make the data reproducing device intricate in arrangement.